Human Health and Ecological Risk Assessment 

for the Use of Wildlife Damage Management Methods

by USDA APHIS Wildlife Services

Chapter XI

The Use of GonaCon in

Wildlife Damage Management

August 2017

Peer Reviewed Final 

July 2022 
i

USE OF GONACON IN WILDLIFE DAMAGE MANAGEMENT

EXECUTIVE SUMMARY

Gonadotropin releasing hormone (GnRH) is a naturally occurring hormone that stimulates 

production of sex hormones such as luteinizing hormone (LH) and follicle-stimulating hormone

(FSH). LH and FSH regulate gamete and steroid hormone production by the ovaries and testes

and are critical in the reproduction of vertebrates. USDA APHIS Wildlife Services (WS) has 

developed an immunocontraceptive vaccine called GonaCon, which includes the active ingredient 

GnRH conjugated to a mollusk-derived carrier protein, against endogenously produced GnRH.

When injected into a target animal, GonaCon induces the body to make antibodies against its 

own GnRH, causing infertility. GonaCon has been shown to be an effective tool in managing 

fertility in wild and feral mammal species. GonaCon is registered for use in female wild or feral 

equids, white-tailed deer, and prairie dogs. 

GonaCon is delivered to the target animal by using preloaded syringes injected by hand or jab 

stick or remote delivery dart for equine and white-tailed deer. Delivery by jab stick or remote 

darting has a greater potential for exposure to human health and the environment due to syringes 

or darts becoming dislodged from the target animal or in the case of remote darting where the 

applicator misses the target animal. The potential for exposure is low because the label requires 

the applicator to attempt to collect syringes or remote darts that become dislodged from the 

animal, or if a remote dart misses the target animal. GonaCon in syringes and darts that aren’t 

located are not anticipated to result in significant exposure to human health and the environment. 

The frequency of GonaCon use is low, the amount of GnRH in the syringes and darts is low and 

is subject to rapid degradation in the environment. 

WS evaluated the potential human health and ecological risks from the proposed use of GonaCon

and determined that the risks to human health and the environment are negligible. Risks to 

workers as well as the general population, including hunters who may harvest injected animals, 

are low based on the method of application, the mode of action of GonaCon, and label 

requirements. Similarly, risks are negligible for nontarget fish and wildlife based on how GonaCon

is applied, its likely environmental fate, and label requirements.
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Table of Contents

1 INTRODUCTION........................................................................................................................................1

2 PROBLEM FORMULATION ......................................................................................................................1

2.1 Chemical Description and Product Use............................................................................................1

2.2 Physical and Chemical Properties....................................................................................................4

2.3 Environmental Fate ..........................................................................................................................4

2.4 Hazard Identification.........................................................................................................................4

3 DOSE-RESPONSE ASSESSMENT..........................................................................................................5

3.1 Human Health Dose-Response Assessment...................................................................................5

3.2 Ecological Effects Analysis...............................................................................................................5

4 EXPOSURE ASSESSMENT......................................................................................................................6

4.1 Human Health Exposure Assessment..............................................................................................6

4.1.1 Potentially Exposed Human Populations and Exposure Pathways........................................6

4.1.2 Exposure Evaluation ...............................................................................................................7

4.2 Ecological Exposure Assessment ....................................................................................................7

5 RISK CHARACTERIZATION .....................................................................................................................8

6 UNCERTAINTIES AND CUMULATIVE EFFECTS....................................................................................9

7 SUMMARY...............................................................................................................................................10

8 LITERATURE CITED...............................................................................................................................10

9 PREPARERS...........................................................................................................................................11

9.1 APHIS-WS Methods Risk Assessment Committee........................................................................11

9.2 Internal Reviewers..........................................................................................................................14

9.3 External Reviewers.........................................................................................................................14

9.4 Peer Review ...................................................................................................................................14

9.4.1 Peer Reviewers’ Agencies Selected by the Association of Fish and Wildlife Agencies.......14

9.4.2 Comments.............................................................................................................................14
1

1 INTRODUCTION

GonaCon is an immunocontraceptive vaccine that was developed and is used by the U.S. 

Department of Agriculture (USDA), Animal and Plant Health Inspection Service (APHIS), Wildlife 

Services (WS) in the management of certain wildlife and feral vertebrate animal populations. This 

risk assessment provides a qualitative evaluation of potential risks and hazards to human health, 

nontarget fish and wildlife as a result of exposure to GonaCon under the proposed uses in the 

APHIS and WS Program. The results of this human health and ecological risk assessment will 

help WS determine an appropriate risk management strategy to achieve its program management 

goal.

The methods used to assess potential human health effects follow standard regulatory guidance

and methodologies (National Research Council 1983, USEPA 2022). The methods used to 

assess potential ecological risk to nontarget fish and wildlife follow U.S. Environmental Protection 

Agency (USEPA) methods, as well as other published methodologies where appropriate. Data 

used in this risk assessment were obtained from USEPA registration-related and other peerreviewed documents, other published literature, and online searches for relevant data. 

The following risk assessment is divided into four sections: problem formulation (identifying 

hazard), toxicity assessment (the dose-response assessment), exposure assessment (identifying 

potentially exposed populations and determining potential exposure pathways for these 

populations), and the integration of the exposure and toxicity assessments, or risk 

characterization.

2 PROBLEM FORMULATION

Wildlife and feral animals can reach population levels that are harmful to ecosystems or the 

human environment. WS employs several lethal and nonlethal methods for managing these 

populations depending on the particular problem. GonaCon is one nonlethal population control 

option -- an immunocontraceptive vaccine that renders female animals temporarily infertile. To 

date, APHIS has obtained USEPA pesticide registrations for use of GonaCon to control 

populations of white-tailed deer1, wild and feral horses (Equus caballus) and burros (Equus 

asinus), and for black-tailed prairie dogs, white-tailed prairie dogs, and Gunnison’s prairie dogs.

APHIS is also investigating the potential for obtaining USEPA registrations to use GonaCon to 

manage populations of bison and feral swine. In experimental studies, GonaCon has also been 

shown to prevent pregnancy in other species including elk, domestic cats, California ground 

squirrels, and brown (Norway) rats (Miller et al. 2008).

2.1 Chemical Description and Product Use

GonaCon is an injectable immunocontraceptive vaccine, containing the active ingredient 

mammalian gonadotropin releasing hormone (GnRH), developed by the WS National Wildlife 

Research Center (NWRC) (Eisemann et al. 2006). GnRH is a 10 amino acid peptide hormone 

with the same amino acid sequence conserved across most mammals (USEPA 2009a). Initially, 

GonaCon was regulated by the U.S. Food and Drug Administration (USFDA) as an investigational 

new animal drug. However, after interagency discussions between USFDA and USEPA Office of 

Pesticide Programs, responsibility for regulatory approval was moved to the USEPA once

research and development of the product by APHIS WS moved toward use of the product as a

1 Scientific names are given in the Risk Assessment Introduction Chapter I,or given if not in that Chapter.
2

wildlife population control tool. USEPA regulates oral and injectable contraceptives when used 

for population control of wild and feral animals (USEPA 2009a). APHIS is currently the registrant 

for three GonaCon end-use products:

• USEPA Reg. No. 56228-40: GonaCon –Deer (for white-tailed deer; registered in November 

2015)2

• USEPA Reg. No. 56228-41: GonaCon – Equine (registered in November 2015)2

• USEPA Reg. No. 56228-64: GonaCon – Prairie Dogs (registered in March 2022)

All three products are GnRH-based water-in-oil emulsions with the same active ingredient 

(0.032% GnRH) and inert ingredients (99.968%). GnRH (also known as luteinizing hormonereleasing hormone (LHRH)) is a reproductive hormone produced in the arcuate nuclei of the 

hypothalamus. GnRH stimulates production and secretion of two gonadotropins (luteinizing 

hormone (LH) and follicle-stimulating hormone (FSH)) by the anterior pituitary gland. LH and FSH 

regulate gamete and steroid hormone production by the ovaries and testes (i.e., estrogen, 

progesterone, and testosterone).

The formulation is comprised of two primary components that are mixed together to form an 

emulsion for injection. The first component is AdjuVac (a mineral oil-based adjuvant that contains 

killed Mycobacterium avium) to induce a localized inflammatory response that triggers a rapid,

strong, and sustained immune response. The second is a mollusk stabilizing buffer (Gionfriddo et 

al. 2011) containing GnRH conjugated to a mollusk-derived carrier protein (i.e., keyhole limpet 

hemocyanin or blue protein) (Bender et al. 2009). Three additional amino acids are added to 

GnRH to act as a spacer and to facilitate conjugation to the carrier protein. Despite GnRH being 

a “self” protein, GnRH conjugated to the mollusk carrier protein causes the body to recognize 

GnRH as “foreign,” stimulating an immune response and production of specific antibodies against 

it. This immune response prevents GnRH from stimulating production of additional sex hormones

(LH and FSH), which blocks ovulation. The target animal becomes temporarily infertile, and 

because the production of sex steroids is also reduced, reproductive behaviors are also often 

suppressed (USEPA 2009b, Killian et al. 2006).

For fertility control in white-tailed deer, single 1-milliliter (mL) doses of GonaCon – Deer (USEPA 

Reg. No. 56228-40) are packaged and pre-loaded in 3-mL plastic syringes. Applicators, who are 

limited to APHIS WS personnel, state wildlife management personnel, or persons working under 

their authority, administer GonaCon by hand injection at least 2 to 3 months prior to the onset of 

rut (USEPA 2009b). The vaccine then induces temporary infertility in female white-tailed deer.

Application by hand-injection into a large muscle mass is done by using a 1.5-inch 18-gauge or 

19-gauge stainless steel hypodermic needle (USEPA 2009b). All vaccinated deer must be tagged. 

A second application can be done by hand injection or remote darting. Application by remote 

darting is done by using a 2 cubic centimeter (cc) dart with a 1.25- or 1.5-inch 14-gauge gelatin 

barb needle. Applicators transfer 1-mL of GonaCon-Deer from the preloaded syringe into the dart. 

In studies, researchers injected GonaCon into the upper hind limb of white-tailed deer and found 

that a single vaccination can induce infertility for multiple years (Gionfriddo et al. 2011). The risks

of using remote darting as an application method for GonaCon – Deer would be similar to those 

discussed below for the equine label, and in the Use of Immobilization and Euthanasia and 

Firearms Risk Assessments.

GonaCon – Equine (USEPA Reg. No. 56228-41) is approved for fertility control in female wild or 

feral horses and burros. Horses and burros receive a single dose (2 mL) of GonaCon – Equine at 

2 Labels can be found @ https://ems-team.usda.gov/sites/aphis-ws/PSD/_layouts/15/start.aspx#/Pesticide%20Labels.
3

least 2 to 3 months prior to the onset of breeding. A single vaccination of GonaCon – Equine can 

induce infertility for multiple years in equids. It has shown similar results in other ungulates, but 

it is not registered for these species (Gray et al. 2010, Fagerstone et al. 2010). GonaCon – Equine 

is administered by hand injection, jab stick, or remote delivery (darting) under the following 

application directions: 

• Hand Injection: Inject 2 mL of GonaCon by intramuscular injection into a large muscle 

mass (e.g., rump, neck) using the preloaded syringe and a 1.5-inch 18-gauge or 19-gauge

stainless steel hypodermic needle

• Jab-Stick Delivery: Transfer 2 mL GonaCon from the preloaded syringe. Inject 

intramuscularly using a 1.5-inch 14-gauge stainless steel hypodermic needle

• Remote Darting: Recommended dart specifications are 2 cc dart with a 1.25 or 1.5-inch 

14-gauge gelatin barb needle. The 2 mL of GonaCon in a preloaded syringe must be 

transferred into the dart. Deliver intramuscularly using the appropriate projection device.

If remote delivery is used, the applicator must make every attempt to recover the dart, whether it 

missed or fell out of the equid. If possible, all darts that are discharged and dropped from the 

horses at the shooting site must be recovered before another darting occurs. In the event that 

spent darts cannot be located due to inclement weather, darkness, or safety concerns, the site of 

a lost dart may be noted and marked, and recovery efforts made at a later date. 

GonaCon – Prairie Dogs (USEPA Reg. No. 56228-64) is approved for fertility control of blacktailed, white-tailed, and Gunnison prairie dogs. GonaCon – Prairie Dogs is administered by 

intramuscular injection into a large muscle in the thigh of individual female prairie dogs. Preloaded syringes are used to administer 0.4 mL of the GonaCon- Prairie Dogs formulation using a 

20- or 23-gauge stainless steel hypodermic needle. The initial injection is administered at least 

two to three months prior to the onset of breeding. A second vaccination (0.4 mL) can be 

administered after 90 days from the initial injection for a total of two vaccinations per individual 

prairie dog per year. The label recommends that applicators mark the fur of vaccinated prairie 

dogs to ensure that they are not unintentionally reinjected during the same application period.

GonaCon - Deer is classified by USEPA as a restricted-use pesticide. All users must be certified 

pesticide applicators or be under the supervision of a certified pesticide applicator. Use of the 

white-tailed deer label is further restricted to USDA APHIS WS or state wildlife management 

agency personnel or persons working under their authority. GonaCon – Equine is a general use 

pesticide that is for use only by employees of federal agencies, federally recognized Indian Tribes, 

state agencies responsible for wild or feral horse and burro management, public and private wild 

horse sanctuaries, research scientists and veterinarians treating wild or feral horse and burro 

populations, or persons working under their authority. GonaCon – Prairie Dogs is a general use 

pesticide that is for use only by employees of USDA APHIS WS or state wildlife management 

agency personnel, or persons working under their authority. All three product labels specify that 

applicators keep these products away from humans, domestic animals, and pets. The labels 

prohibit GonaCon from direct use in water, in areas where surface water is present, or in intertidal 

areas below the mean highwater mark.

Use of all pesticide products also requires a State pesticide registration by individual States. As 

of June 2022, Maryland, New Jersey, and North Carolina have approved the use of the GonaCon

- Deer (USEPA Reg. No. 56228-40), and Arizona, California, Colorado, Idaho, North Dakota, New 

Mexico, Nevada, Oregon, Pennsylvania, Utah and Wyoming have registered GonaCon - Equine 

(USEPA Reg. No. 56228-41). GonaCon – Prairie Dogs (USEPA Reg. No. 56228-64) is approved 
4

for use in Colorado and New Mexico. The labels also specify that users must consult State 

regulations to determine whether they need additional permits or approval prior to use.

2.2 Physical and Chemical Properties

The GnRH (CAS Number: 9034-40-6, and molecular formula: C55H75N17O13) peptide used in 

GonaCon is a white odorless powder, solid at room temperature (USEPA 2009b), with a molecular 

weight of 1182.31 (Merck 2013). Melting point, boiling point, stability to normal and elevated 

temperatures, metal and metal ions, oxidation/reduction action, flammability, explodability, and 

vapor pressure are not available (USEPA 2009b, Merck 2013). Preliminary testing of the GnRH

peptide indicates that it is very water-soluble (≥100 mg/mL) (Warren and Stephens 2008).

GonaCon is a white odorless liquid, the pH is 6.46, and the storage stability is 6 months (USEPA 

2009b).

2.3 Environmental Fate

As part of the data package required by USEPA for registration of GonaCon, APHIS submitted 

waivers for the environmental fate studies because, when used according to label instructions, 

there is limited potential for environmental release from direct injection of the product into the 

target animal. USEPA granted waivers for environmental fate studies including hydrolysis,

photolysis, soil dissipation, aerobic soil metabolism, and adsorption/desorption due to the low 

potential for release to soil and water (USEPA 2009b).

2.4 Hazard Identification 

The role of GnRH within the reproductive system has been intensively studied. However, 

mammalian toxicology data on GnRH is limited to a few acute toxicity studies. The toxicity study 

in deer performed during the safety and toxicity evaluation of GonaCon showed no significant 

contraindications or toxic effects in female white-tailed deer in weeks following vaccination with 

GonaCon, except for the formation of granulomata at the injection site (Killian et al. 2006).

Behavioral studies in white-tailed deer showed that treated animals are not permanently sterilized, 

but they exhibit fewer breeding behaviors due to the decline in serum sex steroids (Killian and 

Miller 2001). A field study in free-roaming feral horses showed that GnRH vaccine can significantly 

reduce fertility for several years with a single injection. However, no significant effects were noted 

from contraceptive treatment on the sex ratio of foals, birthing season, or foal survival (Gray et al. 

2010). With elk, male precopulatory behavior rates toward cows treated with a GnRH vaccine was 

greater than controls and could be problematic; treatment did not affect existing pregnancies or 

calf survival (Powers et al. 2011). However, currently, GonaCon is not registered for use in elk.

Acute oral and dermal studies in the rat showed that all tested animals survived a 1-mL GonaCon 

exposure. A primary eye irritation study for GonaCon in rabbits did not show corneal opacity or 

iritis. Treated eyes exhibited conjunctival redness and discharge within one-hour after treatment, 

but there were no “positive” grade irritations at 24 hours. Rabbits were free of all eye irritation 

after 72 hours. A primary skin irritation study for GonaCon in rabbits did not show swelling at any 

treated site. Initially, treatment resulted in a very slight superficial reddening of skin that dissipated 

within 72 hours. For these reasons, USEPA classified GonaCon as a Toxicity Category IV (no 

precautions required) for acute oral/dermal toxicity and eye and skin irritation exposures (USEPA 

2009b). Chronic toxicity of GnRH is not expected since it is rapidly metabolized in animals.

When GonaCon is used according to the label, human exposure is unlikely. First, certified 

applicators deliver GonaCon while wearing personal protective equipment, which includes long-
5

sleeved shirts, long pants, gloves, and shoes with socks. Secondly, GonaCon is pre-packaged in 

syringes and the preloaded syringes significantly reduce exposure or transferring it to jab stick

syringes or darts presents minimal potential for exposure. Lastly, certified applicators apply 

GonaCon through hand injection (most equids are actually injected using a syringe since they are 

in chutes following roundups) or remote delivery. As a result of these attributes, certified 

applicators are unlikely to have dermal contact with GonaCon or inhale it during its intended use. 

Thus, USEPA waived several study requirements, including:

• The acute inhalation study in the rat because inhalation is unlikely to occur;

• The dermal sensitization study because dermal contact is not expected;

• The studies on gene mutation, structural chromosomal aberration, and other genotoxic 

effects because the intended use precludes human exposure;

• The acute delayed neurotoxicity study in the hen, because GonaCon is not an 

organophosphate pesticide and its structure is not similar to products causing delayed 

neurotoxic effects; and

• The chronic dietary toxicity studies for mammalian and non-mammalian species, because 

GonaCon use will not result in repeated human exposure during its intended use.

The previously described use pattern for GonaCon also resulted in the waiver of ecological effects 

studies required by USEPA for pesticide registration including (USEPA 2009c):

• Seedling Germination/Vegetative Vigor (Guideline 122-1)

• Aquatic Plant Growth (Guideline 122-2)

• Avian Oral Toxicity (LD50) (Guideline 850.1200)

• Avian Dietary Toxicity (LC50) (Guideline 850.2200)

• Acute Toxicity Freshwater Invertebrates (EC50) (Guideline 850.1010)

• Freshwater Fish Toxicity (LC50) (Guideline 850.1075)

USEPA granted waivers for these studies due to the low potential for environmental release of 

GnRH from the proposed use pattern in this assessment.

3 DOSE-RESPONSE ASSESSMENT

3.1 Human Health Dose-Response Assessment

A dose-response assessment evaluates the dose levels (toxicity criteria) for potential human 

health effects including acute and chronic toxicity. USEPA did not establish a reference dose for 

GnRH since it is not considered a food use product and will not accumulate in the tissues of 

treated animals. USEPA assigned GonaCon a Category IV rating for acute oral, dermal, 

inhalation, and ocular exposure routes. A category IV rating means that GonaCon is considered 

practically non-toxic. USEPA waived the requirement for an acute inhalation study during the 

registration of GonaCon (USEPA 2009b); thus, these studies are not available. With the use 

pattern of GonaCon, inhalation exposure is not expected to occur. 

3.2 Ecological Exposure Dose-Response Assessment

USEPA waived the aquatic and terrestrial ecological effects data requirements for GonaCon due 

to its method of application, mode of action, and lack of potential exposure to nontarget fish and 

wildlife. Currently the only available toxicity data applicable to the effects analysis for nontarget 

wildlife is an acute oral limit toxicity study using the rat. No lethal or sublethal effects were noted 
6

during a 14-day period at a dose of 1-mL solution containing 0.03% GnRH (Eurofins 2008). GnRH 

belongs to a large group of peptide-based endocrine-related hormones that are present in all 

vertebrates and are critical for proper reproductive function (Somoza et al. 2002). Sublethal 

effects would be expected in nontarget vertebrates under the appropriate exposure pathway and 

in cases where GnRH is non-specific to binding receptors; however, this is unlikely in nontarget 

fish3 and wildlife since exposure would have to occur through intramuscular injection. GnRH and 

similar peptides have been noted in some invertebrates; however, their role in reproduction and 

other physiological functions is not fully understood (Tsai 2006). Studies regarding these peptides 

are conducted in-vitro and no dose-response data for invertebrates appear to be available in the 

literature.

4 EXPOSURE ASSESSMENT

4.1 Human Health Exposure Assessment

Exposure assessment estimates the potential exposure of humans to GnRH. The exposure 

assessment begins with the use and application methods of the GnRH products. A complete

exposure pathway for GnRH includes (1) release from a GnRH source, (2) an exposure point 

where human contact can occur, and (3) an exposure route for the contact such as ingestion, 

inhalation or dermal contact (USEPA 1989). In this way, the potentially exposed human 

populations and complete exposure pathways are identified and qualitatively evaluated.

4.1.1 Potentially Exposed Human Populations and Exposure Pathways

Exposure of certified pesticide applicators to GonaCon or GnRH is unlikely during proper use;

however, there are potential exposures for trained applicators during an accidental event, or if the 

product is not used according to label directions and precautions. There is the potential for 

accidental exposure during hand injection or remote darting. The GonaCon labels provide caution 

statements about preventing accidental injection. Accidental exposure may also occur through 

faulty darts that discharge accidentally or break during use. This type of exposure to applicators 

is minimized by inspecting darts prior to use and ensuring they are loaded properly. Exposure to 

GonaCon is further reduced by wearing personal protective equipment (PPE) that is intended to 

reduce dermal exposure. PPE for all three GonaCon labels includes long-sleeved shirt and long 

pants, chemical resistant gloves, and shoes plus socks.

The public would not have access to GonaCon. Exposure through consumption of treated animals 

by the public or hunters who consume a recently injected animal is unlikely because GnRH is 

rapidly metabolized and has a short half-life (under one hour) so dietary ingestion of GnRH from 

treated animals is expected to be minimal (see discussion below in Exposure Evaluation for 

additional information on oral exposure). If remote delivery is used, the label requires that 

applicators make every attempt to recover all darts. In addition, the applicators examine all fired 

darts after recovery to determine if the charge fired and the plunger fully expelled its vaccine 

content. Therefore, the potential for the general public to encounter a loaded dart, either from 

failing to recover darts that fall out of treated animals or missing the animal with the dart, is low.

Release of GonaCon or GnRH into soil is unlikely because the vaccine is contained within 

syringes and is injected directly into target animals. The lack of product reaching the soil means 

that subsequent movement and impacts to groundwater via leaching, surface water via runoff, or 

plant uptake are not expected. This excludes the exposure pathway for soil, groundwater, and 

3 Fish as well as other non-mammalian animals produce different forms of GnRH, which reduces the risks even further.
7

surface water media or plant uptake. Loaded darts may occasionally fall out of or miss target

animals and remain on the ground if applicators fail to locate and remove them. If this happens, 

a dose may leak onto the soil, but the volume released would be small. These events would be

infrequent because not all animals are treated using remote delivery methods such as darts, but 

when they are, the chance that WS employees would miss their target is small because 

employees are trained and skilled in remote delivery methods.

4.1.2 Exposure Evaluation

This section qualitatively evaluates the worker exposure in direct contact pathways associated 

with applying GnRH formulations. It also discusses exposure through dietary consumption for 

hunters.

As discussed in Sections 2.4 and 3.1, GonaCon has low toxicity (Category IV) via the oral, dermal, 

ocular, and inhalation routes of exposure. Direct contact exposure from incidental ingestion, 

inhalation, and dermal contact to trained workers wearing (PPE) are minimal. In addition, the label 

prohibits pregnant women from handling or injecting GonaCon. Acute and chronic exposure to 

applicators is negligible. All GonaCon products are contained within pre-loaded syringes 

eliminating the possibility of exposure under labeled use. There is the potential for exposure under 

accidental injection into an applicator during application or during loading a jab stick or a dart. 

This exposure potential is reduced through proper training and handling of animals during field 

operations using any of the GonaCon products.

People could eat a GonaCon-treated animal harvested through hunting. The risk from this type of 

exposure is negligible since the label requirement for GonaCon-Deer requires all vaccinated deer 

to be tagged. This will notify the public that any harvested white-tailed deer have been vaccinated. 

Equine and prairie dogs that are vaccinated with GonaCon are not required to be tagged but are 

not anticipated to be harvested for human consumption. However, if somebody harvests and 

consumes a tagged white-tailed deer, the likelihood of exposure through ingestion is expected to 

be very low for humans, based on the short half-life (less than 1 hour) of GnRH in the animal 

relative to the harvest date, and degradation in the digestive tract prior to absorption. The half-life

of synthetic GnRH was reported as 4 to 12 minutes (Warren 2006). A short half-life indicates that 

GnRH is rapidly metabolized in treated animals and would not be available for human exposure

by the time of dietary consumption. The half-life of the conjugated GnRH is expected to be longer 

at the injection site when compared to GnRH, but conjugated GnRH would not be biologically 

active and would degrade prior to the animal being harvested. Even if a human consumed a 

treated game animal shortly after administration, it is unlikely that he or she would be adversely 

affected because the active ingredient GnRH is a protein that is digested into its component amino 

acids instead of absorbed intact in the digestive tract of mammals. Therefore, oral exposure to 

GonaCon products is not an effective exposure route for humans and animals compared to the

injection route (USEPA 2009a).

It is possible that the public could encounter a dart that has fallen on the ground from a targeted 

animal (either the dart falls out of the animal or the applicator misses the animal with the dart); 

however, GonaCon would likely be contained within the syringe or have been evacuated as a 

result of contact.

4.2 Ecological Exposure Assessment

Aquatic exposure to GnRH is unlikely based on the method of application and short half-life once 

animals are injected. In a scenario where an animal is injected and subsequently dies, due to 
8

other causes, no residues are expected that could runoff or leach into sediment or water.

Secondary exposure to terrestrial nontarget wildlife should also be considered. The extremely 

short half-life and the lack of effects from ingestion of GnRH due to breakdown in the gut would 

not result in a direct or secondary exposure pathway for non-target vertebrates. The short halflife would also reduce the potential for exposure to any invertebrates that may feed on injected 

animals or carcasses. Loaded darts may fall out of or miss target animals and remain on the 

ground if applicators fail to locate and remove them. Loaded darts that fall out of an animal would 

not be expected to contain GnRH since it would most likely have been discharged when the dart 

contacted the target animal. In cases where the contents from a remote delivery are not 

discharged, for example if the target animal is missed, the probability of exposure would also be 

low since it would be unlikely that nontarget wildlife would ingest the syringe and it is likely the 

contents would have been evacuated when the dart strikes the ground or other object. 

GonaCon has caused injection-site and lymph node reactions, which include abscesses, nodules, 

swelling and stiffness from the water-in-oil emulsions containing mycobacteria such as AdjuVac 

(Gionfriddo et al. 2011), but not in all studies (Gray et al. 2010). Curtis et al. (2008) noted 

granulomas in virtually all deer that were vaccinated with GnRH. Vacuoles in the lymph nodes 

were found in cytoplasm or among macrophages and multinucleated giant cells, which were likely 

mineral oil droplets from the AdjuVac. However, injection site reactions to the vaccine did not 

result in observed differences in an animal’s range of movement or locomotor patterns. Thus, a 

side effect can be injection site reactions, but these did not have any noted effects on mobility. 

Injection site and lymph node reactions may be necessary immune system responses that 

precede infertility (Gionfriddo et al. 2011).

The method of drug delivery may be responsible for some injection-site reactions. More injectionsite reactions were observed in remote delivery compared to syringe injection with porcine zona 

pellucida (PZP) (Roelle and Ransom 2009), another immunocontraceptive agent. Rifle darts 

caused less injuries than blowpipes. Roelle and Ransom (2009) determined that the method of 

delivering the drug was likely the cause of injuries since hand injection resulted in few injuries 

whereas dart trauma was much higher. 

5 RISK CHARACTERIZATION

This section qualitatively characterizes risks associated with human health and nontarget fish and 

wildlife. Under the anticipated uses, GonaCon will pose minimal risks to human health as well as 

nontarget fish and wildlife.

GonaCon products contain only 0.032% GnRH as active ingredient, and the remaining 99.968% 

of the formulations are other ingredients that cause an immune response and enhance the 

stability of the vaccine in the treated animal. Applicators administer the vaccine by injection (hand, 

jab stick, or remote darting). Trained applicators must use required PPE and follow other label 

directions to minimize exposure and risk. GonaCon has a Toxicity Category IV for the registered 

uses regarding acute oral, dermal, inhalation, and ocular and skin irritation toxicities. The low 

potential for exposure to GonaCon during intended use combined with the use of PPE and low 

toxicity suggest that adverse health risk to applicators is not expected.

Risks to consumers of hunted game animals are minimal based on the exposure evaluation 

discussed in Section 4.1.2.

GonaCon products pose negligible risk to terrestrial and aquatic nontarget plants and animals.

The lack of ecological risk is due primarily to the proposed use pattern of GonaCon, which 
9

includes hand injection, jab stick, or remote darting, which greatly reduces the potential for any 

exposure to nontarget fish and wildlife either directly or from residues on soil, water, or plant 

material. The requirement for intramuscular injection for activation as well as the short half-life 

further reduces the risk to nontarget organisms. Direct risk to nontarget fish and wildlife and any 

impacts to habitat or prey items (indirect risk) would not be expected to occur under the proposed 

use pattern for GonaCon. 

6 UNCERTAINTIES AND CUMULATIVE IMPACTS

The uncertainties associated with this risk evaluation arise primarily from the unpredictability 

associated with human behavior and can only be discussed qualitatively. Accidental release of a 

small amount of GonaCon from a hand application may occur when GonaCon in the preloaded 

syringe is not accurately delivered to the target animal or the loaded syringe becomes detached.

Accidental self-injection when administering GonaCon to the target animal may also occur.

However, the potential for these accidental exposures is very low with trained and experienced 

applicators. Accidental exposure from transferring the contents of a preloaded syringe into a jab 

stick hypodermic needle or a dart could occur with similar risks as accidental self-injection. These 

risks are expected to be very low. Finally, accidental injection could occur as a result of the dart 

missing its target. However, this would be negligible since WS applicators are trained to use

firearms (certified) and know what their backstop is should the dart miss the intended target 

animal.

WS does not necessarily record the application method (hand injection, jab stick, or dart) used to 

treat target animals with GonaCon, just that it was treated with GonaCon. As this is unknown, and 

data is unavailable on the frequency with which darts fall from or miss target animals, and how 

often applicators are able to recover these darts, APHIS WS cannot exactly determine how much 

GnRH would end up in the environment. However, the amount is expected to be small because 

APHIS applicators make every attempt to recover all darts. In addition, the low volume of GnRH 

in each syringe, the expected short half-life, and the infrequent occurrence of a remote delivery 

miss where the dart is not collected, would equate to minimal amounts of GnRH in the 

environment; in all likelihood discharges in the environment would be expected to quickly result 

in undetectable residues. Any GnRH that would occur in the environment from this type of release 

would be localized to the area immediately adjacent to a compromised syringe and would be 

expected to quickly dissipate.

The independent potential impacts to human health and the environment of the inert ingredients 

in the GonaCon formulation have not been determined in toxicity studies. Previously discussed

inert ingredients in the formulation occur in minor quantities. Other inert materials that occur in 

larger quantities have been evaluated and determined to be practically nontoxic to humans and 

nontarget organisms. In addition, potential exposure of humans and nontarget organisms to the 

formulation, due to the low volume and method of application, as discussed is low, and therefore 

the risk from the formulation is expected to be negligible.

Potential cumulative effects could be associated with: (1) repeated worker exposure to GonaCon 

or GnRH, (2) co-exposures to other pesticides within the program with respect to their toxicity,

and (3) exposures to other chemicals affecting the toxicity of GnRH. Repeated exposure to 

GonaCon or GnRH by applicators wearing appropriate PPE is not expected. In addition, 

vaccinations are injected using prefilled syringes. An accidental exposure may occur if a syringe 

breaks and the contents spill. However, this occasional accidental exposure will not lead to 

accumulation in the human body. WS does not use other pesticides with the same active 

ingredient as GnRH, so exposure by applicators to multiple pesticides with the same mode of 
10

action will not occur. Cumulative effects involving other chemicals that can affect the endocrine 

system are possible for human and ecological exposures. However, it is highly unlikely for WS 

personnel to be simultaneously exposed to GonaCon and these other types of agents. Similarly,

the low potential for GnRH to occur in soil, water, or plants makes cumulative impacts from 

exposure to other endocrine modulating chemicals and GnRH highly unlikely for nontarget fish 

and wildlife.

7 SUMMARY

This risk assessment has determined that the human health and ecological risks from the 

proposed use of GonaCon are negligible. Risks to workers as well as the general population, 

including hunters who may harvest treated animals, are low based on the method of application, 

the mode of action of GnRH, and label requirements. Similarly, risks are negligible for nontarget 

fish and wildlife based on how GnRH is applied, its fate, and label requirements.

8 LITERATURE CITED

Bender, B. C., D. L. Bergman, K. M. Wenning, L. A. Miller, C. E. Rupprecht, D. Slate, and F. R. Jackson. 

2009. No adverse effects of simultaneous vaccination with the immunocontraceptive GonaConTM and 

a commercial rabies vaccine on rabies virus neutralizing antibody production in dogs. Vaccine 27:7210-

7213.

Curtis, P.D., M.E. Richmond, L.A. Miller and F. W. Quimby. 2008. Physioloigical effects of gonadotropinreleasing hormone immunocontraception on white-tailed deer. Human-Wildlife Interactions. 2(1):68-

79.

Eisemann, J. D., K. A. Fagerstone, and R. Jeanette. 2006. Wildlife contraceptives: a regulatory hot potato. 

Proc. Vert. Pest Conf. 22:63-66.

Eurofins. 2008. Acute oral toxicity – limit dose procedure in rats. Eurofins Product Safety Laboratories, Lab.

Study No. 23211. 28 pp.

Fagerstone K. A., L. A. Miller, G. Killian, and C. A Yoder. 2010. Review of issues concerning the use of 

reproductive inhibitors, with particular emphasis on resolving human-wildlife conflicts in North America. 

Integr Zool 5:15–30.

Gionfriddo, J. P., A. J. Denicola, L. A. Miller, and K. A. Fagerstone. 2011. Health effects of GnRH 

immunocontraception of wild white-tailed deer in New Jersey. Wildl. Soc. Bull. 35:149-160.

Gray, M. E., D. S. Thain, E. Z. Cameron, and L. A. Miller. 2010. Multi-year fertility reduction in free-roaming 

feral horses with single-injection immunocontraceptive formulations. Wildlife Research 37:475-481.

Killian, G., and L. A. Miller. 2001. Behavioral observations and physiological implications for the white-tailed 

deer treated with two different immunocontraceptives. Proc. Wildl. Damage Manage. Conf. 9:283-291.

Killian, G., J. Eisemann, D. Wagner, J. Werner, D. Shaw, R. Engeman, and L. Miller. 2006. Safety and 

toxicity evaluation of GonaCon immunocontraceptive vaccine in white-tailed deer. Proc. Vert. Pest 

Conf. 22:82-87.

Merck. 2013. Gonadotropin-Releasing Hormone. Royal Society of Chemistry, The Merck Index Online.

Accessed 08/18/2022 @ https://www.rsc.org/Merck-Index/monograph/m5831/gonadotropinreleasing 

%20hormone?q=authorize
11

Miller, L. A., J. P. Gionfriddo, K. A. Fagerstone, J. C. Rhyan, and G. J. Killian. 2008. The single-shot GnRH 

immunocontraceptive vaccine (GonaCon) in white-tailed deer: Comparison of several GnRH 

preparations. Am. J. Reprod. Immunol. 60: 214-223.

National Research Council. 1983. Risk assessment in the Federal government: Managing the process. 

NRC Comm. Inst. Means for Assessment of Risks to Public Health. National Academies Press. 190 pp.

Powers, J. G., D. L. Baker, T. L. Davis, M.M. Conner, A. H. Lothridge, and T. M. Nett. 2011. Effects of 

gonadotropin-releasing hormone immunization on reproductive function and behavior in captive female 

Rocky Mountain elk (Cervus elaphus nelsoni). Biol. Reprod. 85(6):1152-1160.

Roelle, J. E., and J. I. Ransom. 2009. Injection-site reactions in wild horses (Equus caballus) receiving an 

immunocontraceptive vaccine. U.S. Geol. Survey Scientific Investigation Report 2009-5038. 15 pp.

Somoza, G. M., L. A. Miranda, P. Stobl-Mazzulla, and L.G. Guilgur. 2002. Gonadotropin-Releasing 

Hormone (GnRH): from fish to mammalian brains. Cell. and Mol. Neurobiol. 22(5/6): 589-609.

Tsai, P. S. 2006. Gonadotropin-releasing hormone in invertebrates: structure, function, and evolution. Gen. 

Comp. Endocrinol. 148:48-53.

United States Environmental Protection Agency (USEPA). 1989. Risk Assessment Guidance for 

Superfund: Human Health Evaluation Manual. Vol. I Part A. Interim Final. Office of Emergency and 

Remedial Response, USEPA, EPA/540/1-89/002. December. Wash., DC.

_____ USEPA. 2009a. Memorandum on GonaConTM Immunocontraceptive Vaccine for Use in White-Tailed 

Deer. USEPA, Section 3 Registration. August 4.

_____ USEPA. 2009b. Pesticide Fact Sheet: Mammalian Gonadotropin Releasing Hormone (GnRH), New 

Chemical, Nonfood Use, USEPA Office of Pesticide Programs, Pesticides and Toxic Substances. Sept.

_____ USEPA. 2009c. Memorandum on Section 3 New Chemical Review for Use of GonaConTM

(Gonadotropin Releasing Hormone, GnRH) in Deer. USEPA-Environmental Effects and Fate Division. 

July 22.

_____ USEPA. 2022. Overview of Risk Assessment in the Pesticide Program. USEPA, Office Pesticide 

Programs. Accessed 8/18/2022 @ https://www.epa.gov/pesticide-science-and-assessing-pesticiderisks/overview-risk-assessment-pesticide-program

Warren, J. 2006. Summary of metabolism data for GnRH: GonaConTM Immunocontraceptive. Unpublished

Report OPPTS 870.7485. USDA-APHIS-WS National Wildlife Research Center, Fort Collins, CO. 68p.

Warren, J., and S. Stephens. 2008. Waiver Request: GonaConTM Water Solubility. Submitted by USDAAPHIS to USEPA Office of Pesticide Programs to meet Guideline OPPTS 830.7840 and 830.7860.

9.0 PREPARERS 

9.1 APHIS-WS Methods Risk Assessment Committee

Writers for “Use of GonaCon in Wildlife Damage Management Risk Assessment”:

Primary Writer: Fan Wang-Cahill 

Position: USDA-APHIS-Policy and Program Development (PPD), Environmental and Risk Analysis 

Services (ERAS), Environmental Health Specialist, Riverdale, MD

Education: BS Biology and M.S. Hydrobiology - Jinan University, Guangzhou, China; Ph.D. Botany 

(Ultrastructure/Cell Biology) – Miami University
12

Experience: Joined APHIS in 2012, preparing human health risk assessments and providing assistance 

on environmental compliance. Prior experience before joining APHIS includes 18 years environmental 

consulting experience specializing in human health risk assessments for environmental contaminants 

at Superfund, Resource Conservation and Recovery Act (RCRA), and state-regulated contaminated 

facilities.

Primary Writer: Jim Warren

Position: USDA-APHIS-Policy and Program Development (PPD), Environmental and Risk Analysis 

Services (ERAS), Environmental Toxicologist, Little Rock, AR 

Education: B.S. Forest Ecology and M.S. Entomology – University of Missouri; Ph.D. Environmental 

Toxicology – Clemson University

Experience: Sixteen years of experience working for APHIS preparing ecological risk assessments and 

providing assistance on environmental compliance. Prior experience before joining APHIS includes 

other government and private sector work regarding ecological risk assessments related to various 

environmental regulations.

Writer: Thomas Hall

Position: USDA-APHIS-WS, Operational Support Staff, Staff Wildlife Biologist, Fort Collins, CO

Education: BS Biology (Natural History) and BA Psychology – Fort Lewis College; MS Wildlife Ecology –

Oklahoma State University

Experience: Special expertise in wildlife biology, identification, ecology, and damage management. Thirtyone years of service in APHIS Wildlife Services including in CO and WY for research and OR, GU, CA, 

OK, and NV for operations conducting a wide variety of programs including bird damage research and 

management, livestock protection (predators and birds), invasive species management, wildlife hazard 

management at airports, property and natural resource protection from wildlife. Has worked with feral 

and wild horses, white-tailed deer, and other species.

Editors/Contributors for “Use of GonaConTM in Wildlife Damage Management Risk Assessment”:

Editor: Nikeeya Ali 

Position: USDA-APHIS-WS, Operational Support Staff, Fort Collins, Colorado, 2017 Sumer Intern 

Education: BS in Communications, South Carolina State University

Experience: Three years as a staff writer for The Collegian Newspaper, one year as Editor-in-Chief. Skilled 

in production, video editing. 

Editor: Andrea Lemay 

Position: USDA-APHIS-Policy and Program Development (PPD), Environmental and Risk Analysis 

Services (ERAS), Biological Scientist, Raleigh, NC

Education: BS Plant and Soil Science (Biotechnology) - University of Massachusetts; MS Plant Pathology 

-North Carolina State University 

Experience: Twelve years of service in APHIS conducting risk analysis. Four years of experience in 

preparing environmental analyses in compliance with the National Environmental Policy Act. 

Editor/Contributor: Jeanette O’Hare 

Position: USDA-APHIS-Wildlife Services (WS), National Wildlife Research Center (NWRC), Registration 

manger, Fort Collins, CO 

Education: B.S. Biology – College of Saint Mary; M.A. Biology – University of Nebraska - Omaha

Experience: Thirteen years of experience working for WS NWRC providing regulatory compliance support 

for the development of wildlife damage management tools. Prior experience before joining APHIS 

includes assessing the environmental fate of pesticides and providing the agency guidance on water 

quality issues at the state government level, and laboratory experience in the fields of pharmacology 

and toxicology, and immunology. 

Editor: Emily Ruell 

Position: USDA-APHIS-WS, NWRC, Registration Specialist, Fort Collins, CO
13

Education: B.S. Zoology and Biological Aspects of Conservation – University of Wisconsin - Madison; 

M.S. Ecology – Colorado State University (CSU); M.A. Political Science – CSU

Experience: Three years of experience with APHIS WS NWRC preparing and reviewing vertebrate 

pesticide registration data submissions and other registration materials, and providing pesticide 

regulatory guidance to WS, WS NWRC, and collaborators. Prior experience before joining APHIS 

includes seven years of conducting field and laboratory wildlife research at CSU, and environmental 

policy research for the U.S. Geological Survey.

Editor: Ryan Wimberly 

Position: USDA-APHIS-WS, Operational Support Staff, Staff Wildlife Biologist, Madison, TN

Education: BS Wildlife Management and Ecology – Northwest Missouri State University

Experience: Special expertise in wildlife biology, ecology, and damage management. Sixteen years of 

service with APHIS Wildlife Services, including operations and research, conducting a wide variety of 

programs, including bird damage research and management, livestock protection, invasive species 

management, wildlife hazard management at airports, property, and natural resource protection. Expert 

in preparing environmental documents for WS programs to comply with the National Environmental 

Policy Act and the Endangered Species Act.

9.2 Internal Reviewers

USDA-APHIS Wildlife Services

Reviewer: Brett Dunlap

Position: USDA-APHIS-WS – State Director, Madison, TN

Education: BS Wildlife and Fisheries Sciences – Texas A&M University; MA Biology – Sam Houston 

State University

Experience: Special expertise in wildlife biology and wildlife damage management. Twenty-eight years of 

service in APHIS-Wildlife Services in TX, WA, CA, KY, and TN conducting and managing operational 

programs directed at managing a variety of mammalian and avian wildlife species associated with 

wildlife disease, invasive species, aquatic rodent, airport/airfield, livestock protection, agricultural 

resources, natural resources, and urban/industrial issues. 

Reviewer: Douglas Eckery, PhD

Position: USDA-APHIS-WS National Wildlife Research Center, Researcher, Fort Collins, CO

Education: BS and MS Animal Science – Brigham Young University; PhD Physiology – Colorado State 

University

Experience: Special expertise in reproductive biology and development of tools for fertility control of 

overabundant wildlife species. Current species of interest include horses, feral swine, dogs, and 

macropod marsupials. Joined WS NWRC in 2013 as a research physiologist and leader of fertility 

control project. Oversees manufacture and product support for GonaCon Immunocontraceptive 

Vaccine. Prior experience includes 17 years in New Zealand leading basic and applied research 

focused on fertility control of the brushtail possum and other marsupials.

Reviewer: Kevin J. Sullivan

Position: USDA-APHIS-WS State Director - Maryland, Delaware and District of Columbia, Annapolis, MD

Education: BS and MS Wildlife Biology – West Virginia University and Mississippi State University

Experience: Special expertise in wildlife damage management. Extensive experience with white-tailed 

deer management in urban environments. Principle Investigator for the Pivotal Study for product 

registration of GonaCon Immunocontraceptive Vaccine (2005).

USDA-APHIS Veterinary Services

Reviewer: Albert Kane, DVM

Position: USDA-APHIS-VS Surveillance Preparedness and Response Services, Senior Staff Veterinarian 

and Epidemiologist, Fort Collins, CO
14

Education: BS Biology – Notre Dame, South Bend, IN; DVM - Virginia-Maryland Regional College 

Veterinary Medicine, Blacksburg, VA; MPVM & PhD - University California, Davis 

Experience: Special expertise in veterinary medicine, wild equids, and horse roundups with the 

APHIS/Bureau of Land Management Horse and Burro Partnership. Have assisted with the use of 

GonaCon.

9.3 External Reviewers

U.S. Department of Interior- Geological Survey

Reviewer: James (Butch) Roelle

Position: USDI-U.S. Geological Survey (emeritus) Wildlife Biologist, Fort Collins, CO

Education: BS Biology – Yale University; MS Wildlife Ecology – University of Wisconsin; Ph.D. Wildlife 

Biology – Colorado State University

Experience: 40 years of experience as a wildlife biologist in various federal agencies. Special expertise

in feral horse population dynamics and efficacy of immunocontraceptive vaccines.

9.4 Peer Review

The Office of Management and Budget requires agencies to have peer review guidelines for 

scientific documents. The APHIS guidelines were followed to have “Use of GonaCon in Wildlife 

Damage Management” peer reviewed. WS worked with the Association of Fish and Wildlife 

Agencies to have experts review the documents.

9.4.1 Peer Reviewers’ Agencies Selected by the Association of Fish and Wildlife Agencies

California Department of Fish and Wildlife

Montana Fish, Wildlife and Parks

Nevada Department of Wildlife

Ohio Division of Wildlife

Texas Parks and Wildlife Department

9.4.2 Comments

Comments regarding concerns with the risk assessment and a response:

1. Comment: It would be appropriate to evaluate the risks of the delivery methods, in this case dart 

gun, blow gun, jab stick, and syringe hand injection because they have the potential to cause 

physical trauma in the target animal, though probably low.

Response: The difference in physical impacts as a result of the delivery method are discussed in 

Section 2.1 Chemical Description and Product Use. Additionally, these tools are analyzed in other 

risk assessments in more detail where appropriate

2. Comment: It is not clear in the document whether or not the two GonaCon products (USEPA Reg. 

No. 56228-40 and USEPA Reg. No. 56228-41) are identical? 

Response: Added that they have the same inert ingredients (99.68%), along with the 0.032% 

GnRH just following the labels.

3. Comment: What proportion of animals would be expected to develop injection site and lymph node 

reactions?
15

Response: Curtis et al. (2008) noted granulomas at the injection site of most white-tailed deer that 

were injected with GnRH. The risk assessment was updated to include this information in Section 

4.2. It is not uncommon for vaccines to cause granulomas in many species including other wildlife, 

pets, and humans.

4. Comment: The recommended needle length is provided for GonaCon-Equine but not for 

GonaCon-Deer.

Response: The risk assessment was updated to discuss the recommended needle length for 

GonaCon - Deer.

5. Comment: Birth control for wildlife population is very popular with the general public.

Response: We agree. 

6. Comment: Although the likelihood of exposure through ingestion of game animals is expected to 

be low based on the short half-life (less than 1 hour) of GnRH in the animal relative to the harvest 

date, it’s worth keeping in mind that in some states, road-killed animals can be salvaged for 

consumption at any time of year. In such areas, should treated animals that could be consumed by 

humans be identified in some manner (e.g., ear tag).

Response: The GonaCon-Deer label under the Use Restriction section states that all vaccinated 

deer must be tagged to identify vaccinated deer. The risks to the public from consuming GonaCon 

treated white-tailed deer is very low and the risk decrease further with the use or ear tags to identify 

vaccinated deer.

7. Comment: It seems it would be prudent, if at all possible, to record data such as route of 

administration, missed shots, how many darts were left in the field, how many darts failed to fire 

(how many animals were treated). Data such as number of times a dart wasn’t recovered, number 

of accidental contact with GonaCon, etc. would be valuable to include.

Response: Some of this type of data may be collected when WS is using GonaCon - Equine, 

GonaCon - Deer, or GonaCon - Prairie Dogs. Accidental exposures would be recorded and 

reported to USEPA under FIFRA 6(a)2 adverse effect reporting.

8. Comment: The document has no data to back up many of the risk claims, especially relating to 

personnel administering GonaCon, like other risk assessment documents such as “The Use of Nets

in Wildlife Damage Management.” 

Response: WS has not used GonaCon operationally for white-tailed deer and, therefore, does not 

have data related to use. 

9. Comment: Some clarification on page 2 as to why hand-injection is the only option for white-tailed 

deer would be helpful to discern its risk differences over equine GonaCon.

Response: Since the peer review of this risk assessment APHIS has received approval from 

USEPA to administer GonaCon - Deer using remote darting when administering the second dose.

The risk assessment has been updated to reflect the most current use pattern for GonaCon - Deer.

10. Comment: Seems to be a discrepancy regarding word usage for locating/retrieving missed/fallen 

out darts. On page 3 in the fourth bullet point it says, “can make note of the location” leading one 

to believe it is an option to the applicator by using the word “can”. But on page 6 it says, “label 

requires that applicators make every attempt to recover”. Possibly noting internal policy related to 

this would also be beneficial as I assume it is covered in the Use of Immobilization Risk 

Assessment.
16

Response: The fourth bullet on page 3 was updated to reflect current label language. Applicators 

using remote darting when injecting GonaCon-Deer or GonaCon-Equine must make every attempt 

to recover lost or fallen darts. In situations that prevent searching for lost or fallen darts such as 

inclement weather or darkness, the labels state that applicators may note the location and continue 

searching later. 

11. Comment: On page 3 it states, “labels specify that applicators are not to use these products near 

humans, domestic animals, or pets.” It would then seem prudent to include some discussion on 

the use of GonaCon, especially related to white-tailed deer, in urban environments

Response: This was a mistake and changed to read that the product is to be kept away from 

humans, domestic animals and pets, which primarily refers to storage and use. People involved in 

the use of the product, the applicators, also need to ensure that while they are using the product, 

others are not allowed access to the product. With the use of remote darts, applicators are to make 

every attempt to retrieve darts that miss the target. The risk assessment was updated to reflect 

current label language that states that all of the GonaCon products should be kept away from 

humans, domestic animals, or pets. 

12. Comment: Section 2.4 notes, “With elk, no male precopulatory behavior...” Is this the same for 

white-tailed deer?

Response: This type of behavior has not been noted in white-tailed deer in research.

13. Comment: In Sections 2.4, 4.1.2, and 6, it should be noted the potential for dart failure (ex. 

accidental discharge of a dart, dart body integrity failure, etc.) as a means for potential exposure.

Response: The risk assessment exposure evaluation section was updated to include failed darts 

as a pathway of exposure.

14. Comment: Regarding human exposure, I didn’t see any mention as to whether, both short-term or 

long-term, exposure to humans administering GonaCon can have any sterility effects on them. 

Might be helpful to mention that as a risk.

Response: The human health exposure section was updated to address whether short- or longterm exposure can result in sterility effects. In general, the potential for exposure and subsequent

risk is negligible under normal use. Exposure would only occur under accidental injection of 

GonaCon by an applicator during use. 

Comments received not requiring a response.

1. Comment: I have reviewed the risk assessment and see no reason to discontinue or curtail its use 

in anyway.

2. Comment: I have reviewed the risk assessment and believe the methods described are adequate 

to achieve their purposes.

3. Comment: Overall this document is fairly well written regarding GonaCon. 

Peer reviewers provided a few editorial comments on the manuscript. These were appreciated 

and incorporated into the final document.